A scanning electron microscope (SEM) which is one of the charged particle beam apparatuses scans a micro object with a finely focused electron beam. In this manner, the device emits a secondary electron from the sample, and observes, inspects, or measures the micro object, based on the secondary electron.
PTLS 1 to 3 disclose a method of controlling a lens which is one type of an optical element of an SEM. PTL 1 discloses that a wider aperture angle of a beam to be emitted to the sample provides a high-resolution image to be formed based on the beam emitting, and discloses a control method of controlling a voltage to be applied to the sample so that a predetermined aperture angle α is obtained in order to emit the beam at a large aperture angle. PTL 2 discloses an SEM including a lens for focusing the beam so that an orbit of an electron to be emitted toward the outside of a detector within the secondary electrons emitted from the sample is oriented to the detector. In addition, PTL 3 discloses an SEM including a lens for optimally adjusting an orbit which is incident on an energy filter arranged between the detector and the sample.